Roof guard for open hearth



Nov. 26, 1940. J. KIREN ROOF GUARD FOR OPEN HEARTH Filed Feb. 18, 1959 fo e K fre/1 INVENTOR,

ATTORNEY,

Patented Nov. 26, 1940 UNITED STATES PATENT ,oFFleE 3 Claims.

0 said roof' which heretofore have usually resulted in the collapse of a major portion of the roof structure as the upward buckling of a localized section of an open hearth roof breaks the arch formation thereof with the result that' a major portion of the roof collapses inwardly;

A still further object of this invention is the provision of a roof guard structure for open hearth furnaces so formed that it can be eectively utilized when re-roong the said furnace as it provides an excellent scaffolding structureA from which forms may be hung upon which a new roof structure may be built. This feature of the device is highly important from a time saving point of view'as heretofore it has been necessary to place wooden forms within the furnace itself and rebuild the roof upon the same. The useful life of an open hearth furnace is limited by the durability of the materials used in its construction, namely the refractories of which the walls, the roof, the hearth and like parts are formed and the metal elements employed for binding these parts together such as the buckstays and the tierods, etc. Obviously the cost of maintaining the furnace in operating condition is affected by the life of the refractories used and particularly the life of the roof section of the furnace. Under normal conditions the furnace may be used as high as three hundred times before the refractories comprising its structure become burned thru, at which time it is necessary to rebuild the furnace.

I However, it has been found that in a large number of cases the roof portion of the furnace tends to buckle upwardly in localized areas due,

of course, to the extreme heat and the resulting expansion of the refractory material used. It is not uncommon for such roof buckling to occur when a furnace has been used only a. relatively few times. Thus, it is obvious that any means that will eectively prevent this upwardly buckling of the roof and the resultant collapse of the same will have a practical utility in maintaining the life of the open hearth furnace.

'Ihe present invention has. therefore, as its principal object the provision of a metallic structure adapted to restrain the upward buckling of any portion of the open hearth roof structure; it being understood that suiiicient allowance has been provided for the normal upward expansion of the said roof. Many attempts to 5 eliminate roof collapse have been made, some of the most common being the provision of various types of interlocking r'oof structures involving the use of complicated forms of the refractory materials used. The most common at- 10 tempt at preventing the upward buckling ofportions of the roof structure as heretofore known to the art has consisted in simply placing weights of various natures upon the portions of the roof exhibiting a buckling tendency. l5

The device shown and described herein will effectively resist the upward buckling of any localized area of the roof of the open hearth furnace and thus postpone the collapse of the roof of the said furnace until the end of the full 20 normal life of the refractory used in the roof structure.

With the foregoing and other objects in view which will appear as the description proceeds, the invention resides in the combination and ar- 25 rangement of parts and in the details of construction hereinafter described and claimed, it being understood that changes in the precise embodiment of the invention herein disclosed, can be made within the scope of what is claimed, 30 without departing from the spirit of the invention. 'y

T he invention is illustrated inthe accompany- 4ing drawing, wherein- Figure 1 is a top plan view of a roof guard 35 structure showing it positioned on the buckstays of an open hearth furnace.

Figure 2 is an enlarged sectional end elevation taken on lines 2--2 of Figure 1 and is in eiect an end elevation of an open hearth furnace 40 showing the roof guard positioned above the roof portion thereof.

By referring to the drawing and Figures 1 and 2 it will be seen that the roof guard comprises a plurality of arched steel beams I positioned 45 over the roof 2 of an open hearth furnace by means of stringers 3 positioned on the buckstays 4 of the open hearth furnace. By referring to Figure 2 of the drawing it will be seen that these arched steel beams I are bolted se- 50 curely to the buckstays 4 along the front section 5 of the open hearth furnace and are horizontally movable between the stringers 3 at the back of the open hearth furnace. Carried by these arched steel beams I there are a plurality 55 v of transverse steel beams 6 which are welded or otherwise aiilxed to the under sides of the arched steel beams I in such manner that an effective web )of steel beams is positioned slightly above the roof of the open hearth 2. These transverse steel beams 6 are all preferably permanently aflixed to the arched steel beams I with .the exception of those numbered 1 in the central section 8 of the roof guard. These two sections 'I of the transverse steel beams 6 are preferably separate sections which are bolted to the remaining structure at points 9 so that they are removable'in order to permit a large piece of steel to be placed in the open hearth furnace thru the roof thereof when desired, preferably when the furnace is being rebuilt, it being understood that the piece of steel forwhich provision for insertion thru the roof is made, is of a size prohibiting its being placed in the open hearth furnace thru the usual charging doors located in the front section 5 thereof.

By reference to Figure 1 of the drawing it will be seen that the transverse steel beams 6 and the arched steel beams I are shaped (at the top of Figure 1) to conform with the outwardly tilting back structure I Il of modern open hearth construction, wherein, the back wall of the open hearth furnace has been tilted backwardly -to enable repairs to be made to the same more readily, as, for instance, when such repairs are eiected thru the application of dolomite to this back wall'by means of a dolomite gun; the outwardly tilted section I0 resulting in an additional arch span of the roof 2 over the majority of the area of the furnace which further weakens the roof structure due to the longer arch required. In actual practice it has been found that this outwardly tilted back wall construction and the resulting longer arch of the roof structure immediately above it has materially decreased the life of the roof structure, making the same more liable to buckling than was normal prior to the adoption of this tilted back wall type of open hearth. The roof guard structure shown and described herein has, therefore, a very practical application on this type of open hearth furnace and has been shown and described as taking a form adapted to be so used. By referring to Figure 2 of the drawing it will be seen that the expansion of the roof 2 will close the space between it and the arched steel beams I at which time the plurality of transverse steel beams 6 will come in contact with the roof structure. In this connection it will be observed that there is substantially more clearance provided at the apex of the roof structure than at the sides thereof in Athat any further expansion and particularly buckling upwardly of any localized area will be effectively resisted by the roof guard structure,

and such expansion as results in the roof guard structure is provided for thru the slidable engagement of the same where it is positioned between the stringers 3 along the back of the open hearth furnace, so that the expansion of the roof guard structure itself results only in a horizontal movement in relation to the supporting structure upon which it is slidably positioned. It is understood that the usual tierods II are utilized to properly position the buckstays 4 in relation to the open hearth furnace.

It is understood that the references herein to the outwardly tilted back structure I0 of a modern open hearth furnace has been illustrated in Figure 2 in dotted lines so that some idea may be given as -to the relatively longer arch construction referred to.

What I claim is:

1. A roof guard for open hearth furnaces comprising a grid structure formed of steel beams shaped to conform to the arched roof of an open hearth furnace, the said grid structure positioned on metal frame work of the said open hearth furnace so as to be horizontally movable in relation thereto so as to provide for the expansion thereof, the said grid structure adapted to pre- -vent the upward buckling of any portion of the said roof.

2. The combination of an open hearth furnace and a roof guard, said roof guard comprising a metallic grid shaped to conform to the ar'ched roof of an open hearth furnace, the said roof guard positioned on the metal framework of the said open hearth furnace so as to be horizontally movable in relation there so as to provide for the expansion thereof, the said roof guard adapted to prevent the upward buckling of any portion of the said open hearth roof.

3. A combination of an open hearth furnace and a roof guard for the same comprising a metallic grid structure formed transversely, positioned steel beams carrying a plurality of longitudinally positioned steel bars, the said metallic grid structure positioned on the said open hearth furnace so as to prevent the upward buckling of any area of the said roof, a central section of the said grid structure to permit charging of the open hearth furnace through the roof.

JOEKIREN. 

